This invention relates to a voltage control system for an integrated circuit (IC). More particularly, it relates to a voltage control system that selects the voltage of the IC based on the detection of the effective channel mobility of the IC.
The personal computer has continued its trend of delivering better performance at a lower cost. However, in order to continue delivering these features, new methods of designing computers need to be developed. When the processors inside computers are operating at high clock speeds, the power consumed by the processors increases dramatically. This increased power is dissipated in the computer as excess heat. When the excess heat is not properly controlled or removed from the computer, the user of the computer may experience erratic behavior, system failure, or extremely hot surfaces which may burn, possibly causing injury.
This increase in power is especially a concern in the design of other portable electronic devices such as handheld personal data assistants, calculators, and notebook computers, to name a few. This concern is due not only to the increased chance of physical contact with hot areas on the device but also due to the fact that increasing the power reduces the battery operating time of the device. Users of notebook computers, in particular, do not want to sacrifice performance for longer battery life. They insist on both. Indeed, for a marketable product, a notebook computer should deliver substantial parity with desktop computer performance and provide adequate battery life, preferably greater than two hours.
New models of processors for notebook computers, however, will be consuming more power themselves than the power consumed by an entire notebook computer of previous generations. One proposal to address this increased power is to allow desktop performance when a notebook computer is attached to a xe2x80x9cdocking stationxe2x80x9d which has additional heat dissipation capabilities such as larger fans or heat sinks. When the notebook computer is removed from the docking station, the processor in the notebook is operated at a lower speed to reduce power, notwithstanding, this also reduces performance. Previous market data has shown that users do not wish to lose their performance while operating their notebook remotely. The proponents of this proposal assert that with the increased performance capability of the processor, even reducing the performance by 50%, there is adequate performance at this slower speed for most tasks. However, this assertion is true even with current generation notebook computers and users simply have chosen not to operate their notebook computers in this fashion. Since the trend in computers is for ever higher clock speeds in processors, this problem of meeting both performance and providing adequate battery life is just going to get worse.
Additionally, in order to keep the cost of portable electronic devices acceptably low in to the consumer marketplace, manufacturers of the devices have typically designed them to operate at substantially indoor environmental conditions. The aforementioned need to meet increased performance goals has also required the manufactures to tighten the design specification tolerances, such as temperature, to insure reliable operation. Many users, however, are needing to use their electronic devices, such as notebook computers, remotely in environments which may exceed the design specifications of the device. Such examples are data collection tasks in hot, dry deserts, rainforests, and also frigid ice and snow covered mountains. One solution is to provide a special case in which to enclose the product in order to maintain an adequate operating environment. This solution, however, increases the cost and restricts the operational convenience.
A method and apparatus for efficiently operating an integrated circuit in an electronic device by controlling the supply voltage to the integrated circuit (IC). A parameter of the IC is measured and used to adjust the supply voltage of the IC. The measured parameter is indicative of the effective channel mobility of the IC. One purpose of adjusting the voltage is to modify the effective channel mobility such that the individual channel currents are substantially constant over a predetermined operating temperature range of the IC. The modification of channel mobility is chosen to set the individual channel currents at levels that substantially either maximizes operating speed, minimizes power consumption, extends the range of operating temperature, or increases the operational reliability of the IC.